1. Field of the Invention
The invention relates to an electromagnetic driving device for lens having an anti-tilt mechanism, in which the anti-tilt mechanism can correct possible sideward tilt of the lens while in operation so as to stabilize movement of the lens.
2. Description of the Prior Art
Please refer to FIG. 1, in which a conventional zooming or focusing lens module is explodedly shown. In this conventional design, a mechanical transmission zooming mechanism 9 is utilized. The mechanism 9 uses a high-cost precision driving element 91 as its source power for a carrier 93 of the lens module 92 and a lot more transmission elements are involved in the mechanism 9. In the art, the aforesaid high-cost precision driving element 91 can be a step motor, a ultrasound motor, a piezoelectric actuator, and so on. Obvious disadvantages of such a mechanism 9 can be seen and well known in complicated structuring, tedious and difficult assembling, substantial occupation and high cost. Also, the mechanism 9 consumes a lot of energy during the operation.
In the early stage, the photography is quite professional, which involves manual photo detecting, manual focusing or zooming, and also manual reeling. Such a human-dependent art causes problems for green hands. In particular, while in a historical and un-repeated scene, a good timing for photography is usually missed for those ill-experienced photographers. Then, in 50's and 60's, machinery automation came in and made people believe that the automation would greatly change aspects in various consumer machineries. In the art of photography, the appearance of the auto photo detecting technique and the electrical reeling mechanism had proven that automation in photography was also possible. At that time, the red-hot auto-focusing system that led to a history-high photo-capturing speed was one of the flags for almost all the renowned camera manufacturers in the world.
Recently, it can be seen that the art of photography gears is focused in providing high-resolution images and, on the other hand, in providing a miniaturized design featuring in light weight, thin thickness, and handful size. It is clear that, in the era of having the camera as one of popular 3C products for ordinary amateur people, the cumbersome zooming lens module driven mechanically by the step-motor is now an obstacle for further miniaturizing the camera products.
At the same time, to replace the conventional step motor and to aim at reducing the volume of the driving mechanism of the lens module, an electronic VCM (Voice coil motor) feedback system is introduced to control the movement of the lens module. Also, integration work among various 3C products for enhancing the visual functions is also prosperous. Such work includes one of integrating the image-capturing function to the mobile communication product (for example, a cellular phone), the personal digital assistant (PDA), and/or the notebook computer.
Nevertheless, operations of all the above-mentioned portable products are limited to their own battery capacities. Hence, a topic and/or a research in providing the zooming or focusing lens module a new driving device that can feature in energy conservation while in operation and also in locating the lens module at a preferable position is definitely crucial to the art.
Furthermore, in all conventional driving devices for lens module, a guiding-mechanism is used to regulate linear back-and-forth movement of the lens module along a predetermined direction. To avoid possible jams or ragged movement of the lens module, appropriate tolerance (i.e. spacing) are inevitable between the movable parts and the stationery parts (for example the axial hole and the axial shaft); however, such space leads to a tilt problem for the lens module both in movement and in stops. The space would also affect the linearity and repeatability of controlling the lens module in positions along the photo axis. In particular, while the tolerance, the straightness, or the surface coarseness in holes is beyond the acceptable values, the image quality of the lens module and/or the precision positioning of the moving lens can be degraded. Apparently, the improvement of the aforesaid shortcomings for the lens driving module is definitely essential to the art.